tulsa



UNITED si'rATr-zskv ,P'Ai'llNlIOFFILCIL d JOHN w. CoAsT, JR., or TULsA, OKLAHOMA, AssIGNoB. To THE PRoCEss COMPANY, or v TULSA, OKLAHOMA, A CORPORATION F MARYLAND.

, La ABT 0F CRACKING- HYDROCABBONS.

` To' all 'whom z't may concern:

Be it known that I, J oHN W.`CoAsT, Jr., a citizen of the United States of America, a resident of Tulsa, in the county of Tulsa, State of Oklahoma, have invented certain new and useful Improvements in Art of Cracking Hydrocarbons, of which the following is a full, clear, and exact description, references being had to the accompanying drawing, forming a part of 'this specification.

This invention relates to improvements in the art of cracking h drocarbons, the main object beingv to general7 providing a safe, economical` and highly eiicient method ofl treating high boiling point hydrocarbons to obtain a morevolatile product known as gasolene, or crudegasoene.

More specifically stated, an object of the inventionais to protect cracking stills from the injurious effects of free carbon and tarry substances known in the art as coke and coke-forming matter. By positively elimidues. A great saving of time and'fuel is effected by operating the stills in thls manner. The method of circulating and collectv ing the coke-forming matter overcomes the danger of overheating and rupturing 7the stills, thereby very materially increasing the y life of the stills and reducing the cost of repairs toA a minimum. This coke-forming matter is not a good conductor of heat, and

in the ordinary cracking stills it accumulates between the fire and the oil, lthus preventlng the free transmission of heat to the oil. Under these conditions, the still becomes overheated, and fuel is 4.dissipated or wasted in?? heating' the coke, instead of being utilized 'as aneicient heating medium for the oil.

Another object of the inventionis to facili# tate the cleaning of the still by causing cokeforming matter to accumulate in receptacles from which it can be easily removed. Another object is togenerallv increase the -eiciency of the apparatus by forcibly circulating the oil from a still through a heating coil and back, thereby further economlaln. in the use of fuel, maintanlng all of the o1 `Speciication of Letters Patent.

' Application led September 27, 1917. Serial No. 193,456.

ly improve this art by Patented Oct.. 12, 1920.

at a desirable high temperature, and enabllng the temperature of all of the oil to be tr'alsed qulckly at the beginning of the opera- 1on. f

A further Objectis to increase the yield of low bolling polnt hydrocarbons by subjecting the oil to treatment in two different feeding devices, as will be hereinafter pointed out. The ressure and temperature of the contents ofp the still are preferably diiferent from the pressure and temperature of the coil, and a -stream vof the oil undergoing distillation is circulated bak and forth, from the still and through the coil.

In the preferred form of the invention, all of the foregoing advantages are obtained by continually circulating a stream of oil from a large cylindrical cracking still, through a pipe coil and then back to the cylindrical cracking still, at the same time separating coke-forming matter from the circulating oil. Thev contents'of the pipe coil may be maintained at a higher temperature and under a higher pressure than the cylindrical still. It may be noted that the relatively small pipe of a coil will withstand a higher pressure than a large cylindrical still. In treating some oils, the pipe coil is maintained at a relatively hi h temperature, and the pressure is regulated so as to. prevent vaporization therein. The heavy hydrocarbons are thus sub'ected to the desired degree of heat, and t ereafter permitted to vaporize at a lower temperature in the large still,where the pressure is low enough to obtain this result. ,y However, both the still and thepipe are preferably main tained under pressure, and at a cracking temperature. If desired, a substantially uniform temperature and pressure may be maintained througlrout the apparatus.

Figure I is a diagrammatical view lof al cracking apparatus adapted for use in carrying out the new method. Y

' Fig. II is an enlarged vertical section ,of one of the strainers, or filters, whereby cokef forming matter is separated from the circulating oil.

In the apparatus shown to illustrate the invention, a large cylindrical cracking still 1 is arranged abovea heating chamber 2 and connected by means' of a vapor plpe 3,

to'an air cooled reflux condenser 4. 5 des-.y I ignates a vapor pipe leading from the reflux vcondenser 4 to a main condensing co11 6 from which the low boiling point product is recovered. The condensing coilv 6 is preferably arranged in a water tank 7.

8 designates a heating pi e, or cracking coil, preferably consisting of) a long coil of relatively small pipe arranged in a heating chamber or furnace 9. An intake pipe 10, leading from the lower end of the coil 8, passes through an end wall of the cylindrical still 1 and is connected to a filter A. 11 designates a pipe section arranged in the lower portion of the cylindrical still 1 and connected to a4 rotary pump 12. AV pipe section 13 leads from the pump` to the filter A.l A power shaft 14, passing through a stuffing box 15 at one end of the cylindrical still, may be rotated to actuate the pump 12. A pinion 16 fixed to the inner end of shaft 14, meshes with an operating wheel 17 on the pump, and `thismshaft 14 may 'be .rotated by transmitting power to a wheel 18 at the exterior of the still.

The pipe coil 8 is provided with a discharge pipe'l9 passing through an end of the cylindrical still and connected to a filter A', the llatter being provided with a discharge pipe 20.

The cracking elements may be heated in any suitable manner, and the temperature of each still may be regulated independently of the other.x In .the structure shown, an il burner 21 is arranged in the heating J chamber 9, and the temperature of the pipecoil may be regulated by adjusting a valve 22 adjacent to the burner 21. The bottom of the large cylindrical still may be heated by`a flame discharged from an oil burner 23, and the temperature may be regulated by adjusting a valve 24. 'To avoid the heat losses usually incurred by discharging hot gases and products of combustion from a heating chamber, a flue 25 leads from the heating chamber 9 to the heating chamber 2. The hot fluid passing from the chamber 9, flows over a baffle 26, then downwardly .through the Hue 25 to the heating chamber 21 below the still 1.' A flue 27 leads from mg chamber 2.

The lters, or strainers, A and A may-be made exactly alike, each Ieferably comprising a screen 30 (Fig. )arranged 1n a housing 31 wherein the coke-forming or strainer, may also include a layer of mineral wool 32 arranged above the screen 30, and a layer of ullers earth 33 betweenthe mat-- ter is separated from the oil. Each filter filter. v 70 While the oil is undergoing distillation,

the rotary pump 12 is operated continually, thereby drawing oil and coke-forming matter through the perforations in the intake pipe 11 near the hot still bottom, the' stream 75 of oil and coke-forming matter being drawn to the pump 12, and forced through the'pipe 13 to the filter A. The free carbon, or cokeforming mattei', accumulates in the filter A,

and the filtered oil is constantly discharged through the pipe 10 to the intake end of the pipe coil 8. A stream of oil is thus taken from the. relatively large. body in the cylindrical still/ 1, and forced through thepipey coil 8 from which it is discharged through '35 the pipe 19, filter A and discharge pipe 20. The stream of oil is force'd through the pipe coil at a high velocity, so as to carry the f coke-forming matter to the filter A", the filtered oil being discharged through the pipe 9 0 20 to the main body of oil in the large still. By circulating and filtering a stream of oil as herein shown, coke-forming matter is constantly drawn, from the lower portion of the `large .still 1 and deposited in the filter 95 A, where it will not in any way interfere with the transmission of heat to the oil.

It is also an advantage to lter the oil before discharging it into the pipe coil. The

usual method ofgcracking hydrocarbons in pipe coils, consists in forcing a fresh charge of unheated oil into the hot coil of pipe,-

without in any way removing coke-forming matter from the `oil. As al result, the coke 1 or carbon accumulates in the small pipe,"

and at some point or points the coil soon becomes clogged with the. coke or carbon,

and it is then usually necessary to discontinue the cracking operation for the purpose of removing the coke from the pipe. There is also danger of overheating the pipe at the coke deposits.ve Therefore, one of the desirable features of the present invention consists in sub'ecting the oil to a cracking operation in t e large cylindrical still, forcing a stream of the hot oil through the pipe, and at the same time' separating free carbon or coke-forming matter from the oil 'before it reaches the pipe. This, of course, will not entirely prevent the formation of coke or carbon in the pipe, so theoil is again filtered in the( filter A before it is returned to the main body in the large still.

It will now be understood that the present invention overcomes, o'r materially reduces. 125` the danger and expense due to the presence of carbon or coke in-th'e` still, at the same time avoiding the loss of heat usually 'due to accumulations of coke'between the fire' and cracking still and also in a pipe. Some oils,

or some constituents of the heavy hydrocarbon oil, will not respond readily to the cracking operation which takes place in only one of the cracking devices. By repeatedly subjecting the oil to the conditions existing in both devices, a more effective cracking operation is obtained, and the yield of loW boiling point liquid is greatly increased.

Owing to the manner in which the oil is circulated, also to the removal of coke from the Walls of the stills, the apparatus can be operated continuously for a considerable period of time, and a fresh charge of oil can be occasionally introduced into the system, by means of a pump 30 anda pipe 31 leading from the pump to the pipe 10.

|The apparatus herein shovvn is particularly adapted for use in cracking high boiling point products of distillation, such, for example, as distillates, or residues, resulting from the distillation of crude petroleum. By regulating a valve 32', in the vapor pipe 5, any desired pressure may be obtained in the large cylindrical still 1. rl`he pressure in ,the pipe may be regulated by adjusting a .valve 33 in the discharge pipe 19. rThe pressure in the large still is preferably greater than 50 pounds per square inch, for example, about pounds per square inch, and the temperature of the contents of the large still preferably ranges from about 600o F. to 800O F.l The loW boiling point vapors passing from the liquid, flow through the vapor pipe 3 and reflux condenser 4 to -the pipe 5 leading to the main condenser 6 from,y

which the low boiling point product ,is re covered.

The tvvo different stills herein shown are preferably maintained at di'erent temperatures and under different pressures, the pressure and temperature in the pipe still being preferably higher than the pressure and temperature in the larger still. The small pipe Will withstand a relatively high pressure and a relatively high temperature. l Byregulating the valve 33', any desired relatively high pressure, for example, 150 pounds per` square inch, can be maintained in the pipe still, While the valve 32 in the vapor pipe 5 is regulated to maintain aplower pressure, for example, 80 pounds per s uare inch, in the large cylindrical still. lthough the temperature of the /pipe coil is relatively high, vaporization of the oil therein canbe prevented by the relatively high pressure, and when the oil is discharged through the pipe 19 to the large still, its lighter constituents are permitted to vaporize under the lower degree of pressure inthe-large still. Many of the heavy fractions which do not respond to the ordinary cracking treatment may be successfully cracked When subjected v i to the high pressure and the high temperature existing in the pipe coil. '0bviously, such treatment increases the yield of lovv boiling point fractions. v Y

Since the large bodyof oil in the cylin- 4drical still 1 is heated-internally by the rela- "i tively hot stream of oil passing from the pipe coil, it is not necessary to-subject the bottom of the large still to the high' temperature usually employed when all of the heat is transmitted directly to the still bottom.

The pipe coil is preferably provided vvith l an intake pipe 40 having branches'lll and 42 for the admission of steam and natural gas. Valves 43 and 44 may be regulated to control the ovv of steam and natural gas,

and When necessary or desirable these valves can be closed, or only one of the valves can be opened to admit only one of the fluids to the intake pipe 40./ rlhe velocity of the oil in-the pipe is increased by introducing the' steam and gas at a relatively high pressure. It is important to note that the circulating stream of oil is confined under pressure and cracked in the presence of steam and gas, preferably natural gas. By mixing the steam and gas With the circulating oil, the yield is increased, and a sweeter and better product having a more desirable initial boiling point is obtained. This seems to indicate that .only a very small percentage of the oil is converted into a fixed gas, or that the natural gas is absorbed in the oil by the action yof steam and a high degree of heat.

The apparatus herein disclosed is claimed in an application filed by me on Sept. 27,

1917, Serial No. 193,457.

l claim l 1. ln the art of cracking petroleum hydrocarbons, the method Which comprises main taining hydrocarbon oil in a cracking still and also in another cracking element,x for'cing a stream of the oil from one' ofthe cracking elements to the other, filtering the stream of oil to separate coke-forming matter therefrom, returning the stream of oil from the last mentioned cracking element to the other, filtering the returning stream of oil to separate coke-formingmatter therefrom, heating and vanorizingtheoil under pressure, and condensing thevapor.

2.- In the art of cracking petroleum hydrocarbons, the method which comprises maintaining va body of oil in a large cylindrical cracking still, continuously ischarging a stream of the oily from said cylindrical cracking still', filtering said stream to separate coke-forming matter from the oil, forcingl the filtered oil through a pipe coil, filtering the stream dischargedv from the pipe coil so as. to separate coke-forming matter from the oil, then discharging the stream of filtered oil into the large cylindrical cracking still, at the Same time heating both the still andv pipe coil, aiid vaporizing the oil under pressure, and condensing the vapor.

3. In the art. of cracking pertoleum hydrocarbons, the method Which comprises maintaining hydrocarbon oil in a cracking coil and also in a crackin" still, forcing a stream of the oil back and forth from one of the cracking elements to the other, heating both cracking elements so as to Vaporize the oil under, pressure, condensing the vapor, maintaining'one of the cracking elements under a higher pressure and at a higher temperature than the other, and regulating the temperature and pressure of each vcracking element independently of the other.

4. In the art. of cracking petroleum hydrocarbons, the method which comprises mainy taining'hydrocarbon'oil in two cracking apparatus, forcing a stream of the oil back and forth from one cracking'apparatus to the other, heating both cracking wapparatus so as to vaporize the/oil under pressure,

A maintaining the contents of one cracking apparatus under-v a higher pressure than the pressure in the other, and condensing the vapor.

5. In the art of cracking petroleum hydrocarbons, the method vwhich comprises" main- Y taining a large vcylindrical cracking still in communication with a pipe coil,A maintaining a relatively large body of hydrocarbon oil l in the cylindrical cracking still, forcibly cirdensing the vapor.

culating a stream of the oil from thercylindrical cracking still, through the pipe coil and back into the cylindrical cracking still heating said still and coil so as to vaporize the oil under pressure, maintaining the contents of the pipe coil under a higher pressure and temperature than the pressure and temperature of the cylindrical still, conducting vapor from the cylindrical still and con- \6. In the art of cracking petroleum hydrocarbons, the methodvvhich comprises forcu ing a stream of hydrocarbon oil from one cracking apparatus to another, maintaining the contents of one of said cracking apparatus at a relatively high temperature and under a relatively high `pressure so as to prevent vaporization of the oil therein, maintaining the contents ofthe other cracking aparatus at a lower temperature and under a rf, latively loW, pressure so as to vaporize the'oil therein, conducting vapor from the last mentioned cracking apparatus, and condensing the vapor.

7 In the art of cracking petroleum-hydrocarbons, the method Which comprises maintaining a large cylindrical cracking still in communication with a pipe coil, maintaining a relatively large body of hydrocarbon oil in the cylindrical cracking still, forcing a strea'l'n of oil through the pipe coil and into the cylindrical cracking still, heating said still and coil, maintaining the contents of the Apipe coil at a relativelyhigh temperature and under a pressure suiiiciently high to prevent vaporization of the oil therein, maintaining thecylindrical cracking still at a relatively low temperature and under a relatively low pressure so as to vaporize the oil therein, and condensing the vapor generated in said cylindrical cracking still.

8. Inthe artnof cracking petroleum hydrocarbons, the method which comprises maintaining a large cylindrical cracking still in pounds per square inch) so as to vaporize the oil therein', and 'condensing the vapor generated in saidcylindrical cracking still.-

In testimony that I claim the foregoing I hereunto aiix my signature.

JOHN W. ooAs'r, JR. 

